I, for my sins, are with TalkTalk. My broadband drops out numerous times a day and at times is as slow as watching paint dry. I eventually rang the support and got some help but nothing really changed. To be honest I never really followed up to try to get the settings better. A female colleague, when she heard I was going to ring the support line, wished me luck On their forum you can submit your settings to improve the service, which is great if you know how to find them. Many times I wished I had never changed from Sky but we are all wise after the fact. If you are happy with the service & cost of your current provider then stay with it.
Stew has definitely got it right though, just look at everybodys opinions about mobile phones.